DESCRIPTION

rename()
renames a file, moving it between directories if required.
Any other hard links to the file (as created using
link(2))
are unaffected.
Open file descriptors for
oldpathare also unaffected.

Various restrictions determine whether or not the rename operation succeeds:
see ERRORS below.

If
newpathalready exists, it will be atomically replaced, so that there is
no point at which another process attempting to access
newpathwill find it missing.
However, there will probably be a window in which both
oldpathand
newpathrefer to the file being renamed.

If
oldpathand
newpathare existing hard links referring to the same file, then
rename()
does nothing, and returns a success status.

If
newpathexists but the operation fails for some reason,
rename()
guarantees to leave an instance of
newpathin place.

oldpathcan specify a directory.
In this case,
newpathmust either not exist, or it must specify an empty directory.

If
oldpathrefers to a symbolic link, the link is renamed; if
newpathrefers to a symbolic link, the link will be overwritten.

renameat()

The
renameat()
system call operates in exactly the same way as
rename(),
except for the differences described here.

If the pathname given in
oldpathis relative, then it is interpreted relative to the directory
referred to by the file descriptor
olddirfd(rather than relative to the current working directory of
the calling process, as is done by
rename()
for a relative pathname).

If
oldpathis relative and
olddirfdis the special value
AT_FDCWD,
then
oldpathis interpreted relative to the current working
directory of the calling process (like
rename()).

If
oldpathis absolute, then
olddirfdis ignored.

The interpretation of
newpathis as for
oldpath,
except that a relative pathname is interpreted relative
to the directory referred to by the file descriptor
newdirfd.

This operation makes sense only for overlay/union
filesystem implementations.

Specifying
RENAME_WHITEOUTcreates a "whiteout" object at the source of
the rename at the same time as performing the rename.
The whole operation is atomic,
so that if the rename succeeds then the whiteout will also have been created.

A "whiteout" is an object that has special meaning in union/overlay
filesystem constructs.
In these constructs,
multiple layers exist and only the top one is ever modified.
A whiteout on an upper layer will effectively hide a
matching file in the lower layer,
making it appear as if the file didn't exist.

When a file that exists on the lower layer is renamed,
the file is first copied up (if not already on the upper layer)
and then renamed on the upper, read-write layer.
At the same time, the source file needs to be "whiteouted"
(so that the version of the source file in the lower layer
is rendered invisible).
The whole operation needs to be done atomically.

When not part of a union/overlay,
the whiteout appears as a character device with a {0,0} device number.

RENAME_WHITEOUTrequires the same privileges as creating a device node (i.e., the
CAP_MKNODcapability).

RENAME_WHITEOUTcan't be employed together with
RENAME_EXCHANGE.

RENAME_WHITEOUTrequires support from the underlying filesystem.
Among the filesystems that provide that support are
shmem (since Linux 3.18),
ext4 (since Linux 3.18),
and XFS (since Linux 4.1).

RETURN VALUE

On success, zero is returned.
On error, -1 is returned, and
errnois set appropriately.

ERRORS

EACCES

Write permission is denied for the directory containing
oldpathor
newpath,
or, search permission is denied for one of the directories
in the path prefix of
oldpathor
newpath,
or
oldpathis a directory and does not allow write permission (needed to update
the
..entry).
(See also
path_resolution(7).)

EBUSY

The rename fails because
oldpath or newpathis a directory that is in use by some process (perhaps as
current working directory, or as root directory, or because
it was open for reading) or is in use by the system
(for example as mount point), while the system considers
this an error.
(Note that there is no requirement to return
EBUSYin such
cases---there is nothing wrong with doing the rename anyway---but
it is allowed to return
EBUSYif the system cannot otherwise
handle such situations.)

EDQUOT

The user's quota of disk blocks on the filesystem has been exhausted.

EFAULT

oldpath or newpath points outside your accessible address space.

EINVAL

The new pathname contained a path prefix of the old, or, more generally,
an attempt was made to make a directory a subdirectory of itself.

EISDIR

newpathis an existing directory, but
oldpathis not a directory.

ELOOP

Too many symbolic links were encountered in resolving
oldpath or newpath.

EMLINK

oldpathalready has the maximum number of links to it, or
it was a directory and the directory containing
newpathhas the maximum number of links.

ENAMETOOLONG

oldpath or newpath was too long.

ENOENT

The link named by
oldpathdoes not exist;
or, a directory component in
newpathdoes not exist;
or,
oldpathor
newpathis an empty string.

ENOMEM

Insufficient kernel memory was available.

ENOSPC

The device containing the file has no room for the new directory
entry.

ENOTDIR

A component used as a directory in
oldpath or newpathis not, in fact, a directory.
Or,
oldpathis a directory, and
newpathexists but is not a directory.

ENOTEMPTY or EEXIST

newpathis a nonempty directory, that is, contains entries other than "." and "..".

EPERM or EACCES

The directory containing
oldpathhas the sticky bit
(S_ISVTX)
set and the process's effective user ID is neither
the user ID of the file to be deleted nor that of the directory
containing it, and the process is not privileged
(Linux: does not have the
CAP_FOWNERcapability);
or
newpathis an existing file and the directory containing it has the sticky bit set
and the process's effective user ID is neither the user ID of the file
to be replaced nor that of the directory containing it,
and the process is not privileged
(Linux: does not have the
CAP_FOWNERcapability);
or the filesystem containing
pathnamedoes not support renaming of the type requested.

EROFS

The file is on a read-only filesystem.

EXDEV

oldpath and newpathare not on the same mounted filesystem.
(Linux permits a filesystem to be mounted at multiple points, but
rename()
does not work across different mount points,
even if the same filesystem is mounted on both.)

The following additional errors can occur for
renameat()
and
renameat2():

EBADF

olddirfdor
newdirfdis not a valid file descriptor.

ENOTDIR

oldpathis relative and
olddirfdis a file descriptor referring to a file other than a directory;
or similar for
newpathand
newdirfd

The following additional errors can occur for
renameat2():

EEXIST

flagscontains
RENAME_NOREPLACEand
newpathalready exists.

EINVAL

An invalid flag was specified in
flags.

EINVAL

Both
RENAME_NOREPLACEand
RENAME_EXCHANGEwere specified in
flags.

EINVAL

Both
RENAME_WHITEOUTand
RENAME_EXCHANGEwere specified in
flags.

EINVAL

The filesystem does not support one of the flags in
flags.

ENOENT

flagscontains
RENAME_EXCHANGEand
newpathdoes not exist.

EPERM

RENAME_WHITEOUTwas specified in
flags,
but the caller does not have the
CAP_MKNODcapability.

VERSIONS

renameat()
was added to Linux in kernel 2.6.16;
library support was added to glibc in version 2.4.

renameat2()
was added to Linux in kernel 3.15.

CONFORMING TO

rename():
4.3BSD, C89, C99, POSIX.1-2001, POSIX.1-2008.

renameat():
POSIX.1-2008.

renameat2()
is Linux-specific.

NOTES

Glibc notes

On older kernels where
renameat()
is unavailable, the glibc wrapper function falls back to the use of
rename().
When
oldpathand
newpathare relative pathnames,
glibc constructs pathnames based on the symbolic links in
/proc/self/fdthat correspond to the
olddirfdand
newdirfdarguments.

BUGS

On NFS filesystems, you can not assume that if the operation
failed, the file was not renamed.
If the server does the rename operation
and then crashes, the retransmitted RPC which will be processed when the
server is up again causes a failure.
The application is expected to
deal with this.
See
link(2)
for a similar problem.